The present invention relates to methods and apparatuses for sterilising beverages. Any beverage may comprise bacteria. Traditionally, during the process of sterilising beverages, i.e., substantially removing, killing or destroying micro organisms, the beverages have been pasteurised, i.e., heated to a temperature above which micro organisms, in particular bacteria, and not excluding yeast, fungi, virus and/or prions are killed. In some, or most instances this may ruin taste components. Thus there is a need to provide a system and a method for sterilising beverages without altering, changing or in any other way substantially changing the beverage.
One way to kill micro organisms, such as bacteria, is electro-poration, or electro-permeabilisation, which is achieved by causing a significant increase in the electrical conductivity and permeability of the cell membrane by an externally applied electric field. This is also utilised in molecular biology, albeit without killing the cells. Pores are formed when the voltage across a cell membrane exceeds its dielectric strength. If the strength of the applied electric field and/or duration of exposure to it are properly chosen, the pores formed by the electrical pulse reseal after a short period of time, during which extra cellular compounds have a chance to enter into the cell. However, excessive exposure of live cells to electric fields can cause apoptosis and/or necroses, i.e. result in cell death, which is desirable when sterilising beverage.
The present invention provides systems and methods for performing sterilisation of beverage based on such a principle. The systems and methods include subjecting beverage to electric fields, preferably without having any direct contact between the electric field generator and the beverage.
Generally micro organisms in the beverage are also subjected to this electric field. Bacteria have a lipid bilayer membrane. The lipid bilayer membrane is a membrane or zone of a membrane composed of lipid molecules, usually phospholipids. Lipids are amphiphilic molecules since they have polar head groups and non-polar fatty acid tails. The bilayer is composed of two layers of lipids arranged so that their hydrocarbon tails face one another to form an oily core held together by Van der Waals interactions, while their charged heads face the aqueous solutions on either side of the membrane.